Ten years ago, our daughter Penny was born. She came into the world with a shock of black hair, piercing blue eyes, and, within hours, a diagnosis of Down syndrome.
We learned the biology quickly: Down syndrome is the popular name for trisomy 21, the presence of three copies of the 21st chromosome instead of the typical two. When she was only a few hours old, the doctors told us she would experience some health problems and cognitive delays. The range of those problems was unpredictable.
“Would you take away the Down syndrome if you could?” I asked myself, and my husband, regularly. At first, the answer seemed obvious. What mother wouldn’t make life easier for her child? What father wouldn’t want his daughter’s life free of obstacles and challenges? Then we started to get to know Penny—her thoughtfulness and humor, her love for books and cheeseburgers, her delight in climbing rocks and holding hands. We started to consider how changing her chromosomal makeup would change her, and as time went on, what had once been an obvious question became more complicated. Eventually, it seemed irrelevant.
Now Penny is 10, and I recently encountered that question once more, when I read about a new study in the journal Neuron explaining some of the structural distinctions in the brains of people with trisomy 21. Researchers took 15 postmortem brains of people with Down syndrome from across the life span—from fetus to toddler to adolescent to adult—and paired each one with a brain from a typically developing patient. Comparing each brain to its partner, they found that the brains of people with Down syndrome had an overall reduction in the “density of myelinated fibers.” Myelin is the white substance that coats axons, the spokes that connect neurons to one another. A reduction in myelin has been linked to a variety of neurological conditions, including multiple sclerosis and Guillain-Barre syndrome, among others.